EDIT: follow up is here: Animating in 2D
Best option here would be to use 2D animation, such as Spine.
@dave made a Spine importer, check it out: https://playcanvas.com/editor/scene/400271
It does pretty much all you need, and is very efficient way of animating 2D stuff, because you don’t need to store each frame texture and download it. But only pieces of animated object and then timeline info about each object transformation.
Plus this has a lot of flexibility, that allows you procedurally move stuff around, check out this project as well: https://playcanvas.com/editor/scene/400447